-use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::macros::FormatArgsExpn;
+use clippy_utils::source::snippet_with_applicability;
use clippy_utils::{is_expn_of, match_function_call, paths};
use if_chain::if_chain;
-use rustc_ast::ast::LitKind;
use rustc_errors::Applicability;
-use rustc_hir::{BorrowKind, Expr, ExprKind};
+use rustc_hir::def::Res;
+use rustc_hir::{BindingAnnotation, Block, BlockCheckMode, Expr, ExprKind, Node, PatKind, QPath, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::sym;
declare_clippy_lint! {
- /// **What it does:** Checks for usage of `write!()` / `writeln()!` which can be
+ /// ### What it does
+ /// Checks for usage of `write!()` / `writeln()!` which can be
/// replaced with `(e)print!()` / `(e)println!()`
///
- /// **Why is this bad?** Using `(e)println! is clearer and more concise
+ /// ### Why is this bad?
+ /// Using `(e)println! is clearer and more concise
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # use std::io::Write;
/// # let bar = "furchtbar";
- /// // this would be clearer as `eprintln!("foo: {:?}", bar);`
/// writeln!(&mut std::io::stderr(), "foo: {:?}", bar).unwrap();
+ /// writeln!(&mut std::io::stdout(), "foo: {:?}", bar).unwrap();
+ /// ```
+ ///
+ /// Use instead:
+ /// ```rust
+ /// # use std::io::Write;
+ /// # let bar = "furchtbar";
+ /// eprintln!("foo: {:?}", bar);
+ /// println!("foo: {:?}", bar);
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub EXPLICIT_WRITE,
complexity,
"using the `write!()` family of functions instead of the `print!()` family of functions, when using the latter would work"
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if_chain! {
// match call to unwrap
- if let ExprKind::MethodCall(unwrap_fun, _, unwrap_args, _) = expr.kind;
+ if let ExprKind::MethodCall(unwrap_fun, [write_call], _) = expr.kind;
if unwrap_fun.ident.name == sym::unwrap;
// match call to write_fmt
- if !unwrap_args.is_empty();
- if let ExprKind::MethodCall(write_fun, _, write_args, _) =
- unwrap_args[0].kind;
+ if let ExprKind::MethodCall(write_fun, [write_recv, write_arg], _) = look_in_block(cx, &write_call.kind);
if write_fun.ident.name == sym!(write_fmt);
// match calls to std::io::stdout() / std::io::stderr ()
- if !write_args.is_empty();
- if let Some(dest_name) = if match_function_call(cx, &write_args[0], &paths::STDOUT).is_some() {
+ if let Some(dest_name) = if match_function_call(cx, write_recv, &paths::STDOUT).is_some() {
Some("stdout")
- } else if match_function_call(cx, &write_args[0], &paths::STDERR).is_some() {
+ } else if match_function_call(cx, write_recv, &paths::STDERR).is_some() {
Some("stderr")
} else {
None
};
+ if let Some(format_args) = FormatArgsExpn::parse(cx, write_arg);
then {
- let write_span = unwrap_args[0].span;
let calling_macro =
// ordering is important here, since `writeln!` uses `write!` internally
- if is_expn_of(write_span, "writeln").is_some() {
+ if is_expn_of(write_call.span, "writeln").is_some() {
Some("writeln")
- } else if is_expn_of(write_span, "write").is_some() {
+ } else if is_expn_of(write_call.span, "write").is_some() {
Some("write")
} else {
None
// We need to remove the last trailing newline from the string because the
// underlying `fmt::write` function doesn't know whether `println!` or `print!` was
// used.
- if let Some(mut write_output) = write_output_string(write_args) {
- if write_output.ends_with('\n') {
- write_output.pop();
- }
-
- if let Some(macro_name) = calling_macro {
- span_lint_and_sugg(
- cx,
- EXPLICIT_WRITE,
- expr.span,
- &format!(
- "use of `{}!({}(), ...).unwrap()`",
- macro_name,
- dest_name
- ),
- "try this",
- format!("{}{}!(\"{}\")", prefix, macro_name.replace("write", "print"), write_output.escape_default()),
- Applicability::MachineApplicable
- );
- } else {
- span_lint_and_sugg(
- cx,
- EXPLICIT_WRITE,
- expr.span,
- &format!("use of `{}().write_fmt(...).unwrap()`", dest_name),
- "try this",
- format!("{}print!(\"{}\")", prefix, write_output.escape_default()),
- Applicability::MachineApplicable
- );
- }
+ let (used, sugg_mac) = if let Some(macro_name) = calling_macro {
+ (
+ format!("{}!({}(), ...)", macro_name, dest_name),
+ macro_name.replace("write", "print"),
+ )
} else {
- // We don't have a proper suggestion
- if let Some(macro_name) = calling_macro {
- span_lint(
- cx,
- EXPLICIT_WRITE,
- expr.span,
- &format!(
- "use of `{}!({}(), ...).unwrap()`. Consider using `{}{}!` instead",
- macro_name,
- dest_name,
- prefix,
- macro_name.replace("write", "print")
- )
- );
- } else {
- span_lint(
- cx,
- EXPLICIT_WRITE,
- expr.span,
- &format!("use of `{}().write_fmt(...).unwrap()`. Consider using `{}print!` instead", dest_name, prefix),
- );
- }
- }
-
+ (
+ format!("{}().write_fmt(...)", dest_name),
+ "print".into(),
+ )
+ };
+ let mut applicability = Applicability::MachineApplicable;
+ let inputs_snippet = snippet_with_applicability(
+ cx,
+ format_args.inputs_span(),
+ "..",
+ &mut applicability,
+ );
+ span_lint_and_sugg(
+ cx,
+ EXPLICIT_WRITE,
+ expr.span,
+ &format!("use of `{}.unwrap()`", used),
+ "try this",
+ format!("{}{}!({})", prefix, sugg_mac, inputs_snippet),
+ applicability,
+ )
}
}
}
}
-// Extract the output string from the given `write_args`.
-fn write_output_string(write_args: &[Expr<'_>]) -> Option<String> {
+/// If `kind` is a block that looks like `{ let result = $expr; result }` then
+/// returns $expr. Otherwise returns `kind`.
+fn look_in_block<'tcx, 'hir>(cx: &LateContext<'tcx>, kind: &'tcx ExprKind<'hir>) -> &'tcx ExprKind<'hir> {
if_chain! {
- // Obtain the string that should be printed
- if write_args.len() > 1;
- if let ExprKind::Call(_, output_args) = write_args[1].kind;
- if !output_args.is_empty();
- if let ExprKind::AddrOf(BorrowKind::Ref, _, output_string_expr) = output_args[0].kind;
- if let ExprKind::Array(string_exprs) = output_string_expr.kind;
- // we only want to provide an automatic suggestion for simple (non-format) strings
- if string_exprs.len() == 1;
- if let ExprKind::Lit(ref lit) = string_exprs[0].kind;
- if let LitKind::Str(ref write_output, _) = lit.node;
+ if let ExprKind::Block(block, _label @ None) = kind;
+ if let Block {
+ stmts: [Stmt { kind: StmtKind::Local(local), .. }],
+ expr: Some(expr_end_of_block),
+ rules: BlockCheckMode::DefaultBlock,
+ ..
+ } = block;
+
+ // Find id of the local that expr_end_of_block resolves to
+ if let ExprKind::Path(QPath::Resolved(None, expr_path)) = expr_end_of_block.kind;
+ if let Res::Local(expr_res) = expr_path.res;
+ if let Some(Node::Pat(res_pat)) = cx.tcx.hir().find(expr_res);
+
+ // Find id of the local we found in the block
+ if let PatKind::Binding(BindingAnnotation::Unannotated, local_hir_id, _ident, None) = local.pat.kind;
+
+ // If those two are the same hir id
+ if res_pat.hir_id == local_hir_id;
+
+ if let Some(init) = local.init;
then {
- return Some(write_output.to_string())
+ return &init.kind;
}
}
- None
+ kind
}